UBI: add UBI devices reference counting

This is one more step on the way to "removable" UBI devices. It
adds reference counting for UBI devices. Every time a volume on
this device is opened - the device's refcount is increased. It
is also increased if someone is reading any sysfs file of this
UBI device or of one of its volumes.

Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>

1 files changed, 10 insertions, 24 deletions

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index bc900d24cdba..01978b57e9cb 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -56,23 +56,6 @@
 #endif
 
 /**
- * major_to_device - get UBI device object by character device major number.
- * @major: major number
- *
- * This function returns a pointer to the UBI device object.
- */
-static struct ubi_device *major_to_device(int major)
-{
-        int i;
-
-        for (i = 0; i < UBI_MAX_DEVICES; i++)
-                if (ubi_devices[i] && MAJOR(ubi_devices[i]->cdev.dev) == major)
-                        return ubi_devices[i];
-        BUG();
-        return NULL;
-}
-
-/**
  * get_exclusive - get exclusive access to an UBI volume.
  * @desc: volume descriptor
  *
@@ -129,9 +112,11 @@ static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
 static int vol_cdev_open(struct inode *inode, struct file *file)
 {
         struct ubi_volume_desc *desc;
-        const struct ubi_device *ubi = major_to_device(imajor(inode));
-        int vol_id = iminor(inode) - 1;
-        int mode;
+        int vol_id = iminor(inode) - 1, mode, ubi_num;
+
+        ubi_num = ubi_major2num(imajor(inode));
+        if (ubi_num < 0)
+                return ubi_num;
 
         if (file->f_mode & FMODE_WRITE)
                 mode = UBI_READWRITE;
@@ -140,7 +125,7 @@ static int vol_cdev_open(struct inode *inode, struct file *file)
 
         dbg_msg("open volume %d, mode %d", vol_id, mode);
 
-        desc = ubi_open_volume(ubi->ubi_num, vol_id, mode);
+        desc = ubi_open_volume(ubi_num, vol_id, mode);
         if (IS_ERR(desc))
                 return PTR_ERR(desc);
 
@@ -586,9 +571,9 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
         if (!capable(CAP_SYS_RESOURCE))
                 return -EPERM;
 
-        ubi = major_to_device(imajor(inode));
-        if (IS_ERR(ubi))
-                return PTR_ERR(ubi);
+        ubi = ubi_get_by_major(imajor(inode));
+        if (!ubi)
+                return -ENODEV;
 
         switch (cmd) {
         /* Create volume command */
@@ -695,6 +680,7 @@ static int ubi_cdev_ioctl(struct inode *inode, struct file *file,
                 break;
         }
 
+        ubi_put_device(ubi);
         return err;
 }